Electron-phonon relaxation at the Au/WSe interface is significantly accelerated by a Ti adhesion layer: time-domain analysis.

Thermal transport at nanoscale metal-semiconductor interfaces electron-phonon coupling is crucial for applications of modern microelectronic, electro-optic and thermoelectric devices. To enhance the device performance, the heat flow can be regulated by modifying the interfacial atomic interactions. We use time-dependent density functional theory combined with non-adiabatic molecular dynamics to study how the hot electron and hole relaxation rates change on incorporating a thin Ti adhesion layer at the Au/WSe interface.

Influence of tungsten doping on nonradiative electron-hole recombination in monolayer MoSe with Se vacancies.

Two-dimensional transition metal dichalcogenides (TMDs) are receiving significant attention due to their excellent electronic and optoelectronic properties. The material quality is greatly affected by defects that are inevitably generated during material synthesis. Focusing on chalcogenide vacancies, which constitute the most common defect, we use the state-of-the-art simulation methodology developed in our group to demonstrate that W doping of MoSe with Se vacancies reduces charge carrier losses by two mechanisms.

Quantum dynamics origin of high photocatalytic activity of mixed-phase anatase/rutile TiO.

Mixed anatase/rutile TiO exhibits high photocatalytic activity; however, the mechanism underlying the high performance of the mixed phases is not fully understood. We have performed time-domain ab initio calculations to study the exited state dynamics in mixed phase TiO and to investigate the impact of an oxygen vacancy on the dynamics. The anatase(100)/rutile(001) heterostructures with and without an oxygen vacancy used in this work exhibit type II band alignment with the conduction band of rutile residing above that of anatase.

Thin Ti adhesion layer breaks bottleneck to hot hole relaxation in Au films.

Slow relaxation of highly excited (hot) charge carriers can be used to increase efficiencies of solar cells and related devices as it allows hot carriers to be extracted and utilized before they relax and lose energy. Using a combination of real-time density functional theory and nonadiabatic molecular dynamics, we demonstrate that nonradiative relaxation of excited holes in an Au film slows down 30-fold as holes relax across the energy range -2 to -1.5 eV below the Fermi level.

Rapid Decoherence Suppresses Charge Recombination in Multi-Layer 2D Halide Perovskites: Time-Domain Ab Initio Analysis.

Two-dimensional (2D) Ruddlesden-Popper halide perovskites are appealing candidates for optoelectronics and photovoltaics. Nonradiative electron-hole recombination constitutes a major pathway for charge and energy losses in these materials. Surprisingly, experimental recombination is slower in multilayers than a monolayer, even though multilayer systems have smaller energy gaps and higher frequency phonons that should accelerate the recombination.

Interplay between Localized and Free Charge Carriers Can Explain Hot Fluorescence in the CHNHPbBr Perovskite: Time-Domain Ab Initio Analysis.

Delayed high-energy fluorescence observed experimentally in methylammonium lead bromine CHNHPbBr (MAPbBr) demonstrates long-lived energetic charge carriers with extremely high mobilities that can be used to enhance photon-to-electron conversion efficiency of perovskite solar cells. It has been suggested that hot fluorescence is associated with reorientational motions of the MA molecules. We support this hypothesis by time-domain ab initio quantum dynamics calculations showing that reorientation of the MA molecules can affect strongly the perovskite emission energy and lifetime.